Prior to the development of oral-cavity-imaging-and-modeling systems, dental practitioners employed mechanical-impression methods to create three-dimensional models of teeth and underlying tissue in order to facilitate fabrication of various types of prostheses, including crowns and bridges. The mechanical-impression technologies generally involved biting, by a patient, into a viscous, thixotropic material that retains an accurate impression of the patient's teeth and underlying tissue when the material is lifted off from the patient's teeth. The material may serve as a mold for casting a positive three-dimensional model of the patient's teeth and underlying gum tissue or as a mold for casting a prosthetic device. While mechanical-impression technologies have been used by dental practitioners for many decades, mechanical-impression technologies are associated with a variety of deficiencies, including a relatively large probability that the impression may be inadvertently altered or damaged during removal of the hardened, viscous, thixotropic material from the patient's teeth as well as during transportation of the impression to laboratories where positive three-dimensional models are cast and prostheses are fabricated. In addition, the procedure is time-consuming and unpleasant to many patients.
More recently, semi-automated oral-cavity-imaging-and-modeling systems have been developed to electronically create digital, three-dimensional models of teeth and underlying tissues from images of a patient's oral cavity captured by an electro-optical-mechanical endoscope, or wand, that is guided by a technician within a patient's oral cavity in order to collect a sufficient number of two-dimensional images from which a three-dimensional digital model of the patient's teeth and underlying tissues is computationally generated. The oral-cavity-imaging-and-modeling systems have proven to be faster, more accurate and robust, and more cost effective than mechanical-impression technologies.
In many cases, therefore, dental professionals can prepare accurate, three-dimensional models of a patient's teeth and use the three-dimensional models to analyze the patient's dental status and develop treatment plans for various types of deficiencies and pathologies. Furthermore, the three-dimensional model can be electronically manipulated to prepare projected three-dimensional configurations of the patient's teeth for various time points during the course of a treatment plan. Vendors of dental equipment, dental practitioners, and, ultimately, dental patients seek cost-effective and time-effective methods and systems to use the three-dimensional information in order to monitor a dental patient's progress during a course of treatment.